Twice a year, the time change disrupts people's sleep schedules. It's a biannual ritual that comes with great cost – including a spike in the number of car crashes.

Here are some important things to know as you try to protect yourself against drowsy driving accidents.

Crashes caused by drivers who were sleepy or fatigued are increasing in California.

According to the California Highway Patrol, there were 6,930 crashes attributable to sleepiness or fatigue. This figure increased nearly 50 percent in only two years.

California also has averaged 45 deaths a year in the last three years from drowsy driving.

Pedestrians are particularly at risk.

Following the transition from Daylight Saving Time to Standard Time, the problem isn't only disrupted sleep schedules. It is also the increased hour of darkness in the early evening.

Researchers have found that pedestrians are particularly at risk following the transition back to Standard Time. The sudden change to a much-darker commute increases the risk of pedestrian fatalities.

Falling asleep at the wheel is not an uncommon occurrence.

According to the Centers for Disease Control, the percentage of adults who admit to having fallen asleep while driving may be as much as 1 in 25.

The chances of this happening increase significantly when someone does not get the recommended seven hours of sleep for adults. For teenagers, the amount is eight hours.

Getting the necessary rest is easier said than done in a 24/7 culture in which millions of people have untreated sleep disorders.

Fatigued driving is similar in many ways to drunk driving in how it affects attention and reaction time.

This is why the California Highway Patrol is running a Drowsy Driving Prevention week until November 12.